from abc import ABC, abstractmethod

class Animal(ABC):
    @abstractmethod
    def speak(self):
        pass

class Dog(Animal):
    def speak(self):
        print("Woof!")

class Cat(Animal):
    def speak(self):
        print("Meow!")

class Bird(Animal):
    name = "Song"
    def speak(self):
        print(f"Bird {self.name} is speaking")

bird = Bird()
bird.speak()
